The isolated canine brain preparation will be used as follows: 1) to determine what nutrients (vitamins, coenzymes, fatty acids) enter brain from the blood and to determine if these nutrients enter by diffusion or carrier mediated processes. 2) to correlate the formation of cerebral edema with brain metabolism and blood flow during and after various periods of anoxic-anoxia. 3) to correlate cerebral transport in vivo to in vitro transport in isolated cerebral capillaries. 4) to determine cerebral blood flow changes by the microsphere technique during normal and pathological conditions. 5) to examine cerebral tissue samples for pathological alterations due to the experimental conditions. Bibliographic references: Gilboe, D.D. and Saffitz, M.S. Kinetics of uptake and adrenergic response to norepinephrine in the cerebral vasculature. The Physiologist, 18:224, 1975. Betz, A.L., Gilboe, D.D. and Drewes, L.R. Effects of anoxia on net uptake and unidirectional transport of glucose in the isolated dog brain. Brain Research. 67:307-316, 1974.